Lamotrigine of formula (1):
or 6-(2,3-Dichlorophenyl)-1,2,4-triazine-3,5-diamine is an anti-epileptic drug and its therapeutic uses are disclosed in U.S. Pat. No. 4,602,017.
Different synthetic methods of lamotrigine are described in WO 01/049669, U.S. Pat. No. 6,111,101, U.S. Pat. No. 6,333,198, U.S. Pat. No. 5,912,345, EP 800521, U.S. Pat. No. 4,602,017.
Various polymorphic forms are disclosed in WO 02/068398.
We have discovered three novel crystalline forms of lamotrigine. The novel forms have been found to be stable over the time and does not automatically convert into other crystalline forms of lamotrigine.
The novel forms of lamotrigine are, thus, suitable for pharmaceutical preparations.
Thus the object of the present invention is to provide stable novel crystalline forms of lamotrigine, to provide a processes for preparation of the novel crystalline forms and to provide a pharmaceutical compositions comprising these novel crystalline forms.